Registered: 29th Jun 2012
The locking and radio would still work even if the battery had lost (some) power. If you tur the lights on and try to start it, if the lights dim then the battery has not got enough juice for the starter motor.
If you could get a video and put a link from youtube then it will be easier to diagnose.
Could be the immobiliser. Do any lights come on on the dash that didn't used to? Is there any engine coolant in/enough as I know it was a cold night last night and it could have frozen. Its worth trying to figure it out without trying to turn it over too much because if its something like a serious oil leak/broken belt the engine could get damaged by turning it over.